Uneven, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Even
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Ca2Al3(SiO4)3(OH)
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references